A few years back when I read Cass Sunstein's book "Republic 2.0" I was immediately impressed both by the message and the argumentation. In his most recent book "Going to extremes--how like minds unite and divide" he comes back to the same topic but more grounded and with a broader scope. The topic of this book is the idea of "group polarization". Sunstein defines the phenomenon like this: "When people find themselves in groups of like-minded types, they are especially likely to move to extremes." (p 2). This means that when people meet with other who have similar views they reinforce and strengthen these views, to the point when they may be seen as extreme. This can happen around any topic and Sunstein gives many examples in the book. People may become extreme in their views on politics (something Sunstein uses a lot), health, sports, religion, etc. Sunstein uses the major part of the book to show research that in different ways support this idea. He explores many aspects of the idea and paints a broad and convincing picture of the phenomenon.
The more I read the book the more complex the notion of "group polarization" becomes. Sunstein starts our with more definitional reasoning about how to understand the concept, later he moves on to questions such as if polarization is good or bad, and how or if it is possible to "handle" it. Of course, he also discusses some of the ideas he presented in "Republic 2.0" about internet as a very efficient tool in creating "group polarization", but here he is more balanced in his reasoning and also bring forward and explores "good extremism".
As always, it is a pleasure to read Sunstein. The writing is extraordinary clear and easy to follow. The argumentation is wonderfully straightforward. As you reader you do not have any concerns with not understanding the author. Instead, the clear argumentation really invites the reader to analyze and critique the author.
For anyone who studies groups, communities, organizations, or any other assembly of people, this is a great book. It has implications for anyone thinking about social media and internet usage. However, the book does not makes things easier and it does not give the reader any prescriptions to follow on how to achieve certain group results, but it truly add to a more foundational understanding of group behavior.